The function of the iris is to ....

$A$: Sharpest vision is in fovea centralis.
$R$: The relationship of receptor to bipolar cells to ganglion cells is $1:1:1$ within fovea centralis.

Which of the following results in the generation of potential differences in the photoreceptor cells of eyes?

The anterior portion of the sclera is called:

The image formed on the retina of the eye is ....

When the intensity of light is low during the night,the light is detected by: